BAAP (the British Association of Academic Phoneticians) has just held its biennial Colloquium here in London. As usual, there were some excellent and thought-provoking presentations.
One particularly interesting contribution concerned linguolabial sounds. Linguolabials, articulated by the tongue tip against the upper lip, are very rare in the languages of the world. Nevertheless linguolabial plosives, fricatives, and a nasal are known to occur in a cluster of languages in the island state of Vanuatu. One of these languages is Tangoa. But until now there had been no reliable report of a linguolabial trill, if we discount an extrasystemic onomatopoeic ideophone alleged to be used in Coatlán Zapotec.
However, Olaf Lipor now reports that a voiced linguolabial trill has recently been discovered to be used contrastively in Caslon and Ki-Flong, languages spoken on the island of San Serriffe. The IPA symbol for this newly attested sound-type is r with the ‘combining seagull below’ diacritic, U+033C, thus [r̼].